Facile Multicomponent Polymerizations toward Multifunctional Heterochain Polymers with α,β-Unsaturated Amidines

Heterochain polymers play an essential role in our daily life due to their distinctive properties. Among various heteroatom-rich structures, amidine derivatives serve as a synthetically important and pharmacologically useful structural branch. In this work, we developed a straightforward and powerful polymerization to access diverse heterochain polymers with α,β-unsaturated amidine units. The multicomponent polymerizations of readily accessible diynes, disulfonyl azides, and N,N-dimethylformamide dimethyl acetal proceed efficiently at room temperature, producing amidine-containing polymers with high molecular weights in high yields within merely 1 h. All of the obtained polymers are formed with excellent stereoselectivity for the newly formed C═C adjacent to the amidine group. The introduction of aggregation-induced emission (AIE) luminogen together with the inherent heteroatom-rich structure feature endows these polymers with multiple functionalities. The nanoaggregates of the diethylamino-substituted polymer show remarkable and reversible fluorescence response to acid and base, and the acid-fumed polymer thin film can be used as a sensitive and reusable fluorescent probe for detecting seafood spoilage. This polymer system can also be employed as a highly selective and sensitive Au3+ sensor, and efficient gold recovery can be achieved based on its excellent gold enrichment capability. In addition, the AIE polymers can also be applied in lysosome-specific cell imaging with low cytotoxicity and excellent photostability.